The present application describes systems and techniques relating to network intrusion detection, for example, integrated network intrusion detection.
A machine network is a collection of nodes coupled together with wired and/or wireless communication links, such as coax cable, fiber optics and radio frequency bands. A machine network may be a single network or a collection of networks (e.g., an internetwork), and may use multiple networking protocols, including internetworking protocols (e.g., Internet Protocol (IP)). These protocols define the manner in which information is prepared for transmission through the network, and typically involve breaking data into segments generically known as packets (e.g., IP packets, ATM (Asynchronous Transfer Mode) cells) for transmission. A node may be any machine capable of communicating with other nodes over the communication links using one or more of the networking protocols.
These networking protocols are typically organized by a network architecture having multiple layers, where each layer provides communication services to the layer above it. A layered network architecture is commonly referred to as a protocol stack or network stack, where each layer of the stack has one or more protocols that provide specific services. The protocols may include shared-line protocols such as in Ethernet networks, connection-oriented switching protocols such as in ATM networks, and/or connectionless packet-switched protocols such as in IP.
As packets travel through a network, they are typically encapsulated within other packets multiple times. Encapsulation enables data to travel from a source process on one node to a destination process on another node, through multiple networks using different protocols and addressing schemes, without the two end nodes knowing anything about the intermediate addressing schemes and protocols.
Machine networks may provide powerful communication capabilities, but also may increase the difficulty of maintaining computer system security by making systems and data more accessible. Most networks are susceptible to attacks or improper use, both from inside and from outside the network. Attacks include attempts to gain unauthorized access to data, destroy or bring down a computer system, prevent others from accessing a system and attempts to take control of a system. For example, some network intrusions exploit application anomalies to gain access to a system and infect it with a computer virus, such as Code Red or Nimba.
A common technique used to improve network security is to install a firewall, which restricts and controls the flow of traffic between networks, typically between an enterprise network and the Internet. Firewalls typically monitor incoming and outgoing traffic and filter, redirect, repackage and/or discard packets. A firewall may serve as a proxy and may enforce an organization's security policies.
Frequently, network administrators employ systems to detect network intrusions to improve network security. Traditional network intrusion detection (NID) systems attempt to examine every packet on a network in order to detect intrusions. These NID systems may be implemented as standalone systems (e.g., NFR (Network Flight Recorder), provided by Cisco Systems, Inc. of San Jose, Calif.), or they may be implemented as distributed node-based systems (e.g., BlackICE, provided by Network Ice Corporation of San Mateo Calif.).
Details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features and advantages may be apparent from the description and drawings, and from the claims.